Negative neuromuscular and functional repercussion of forced swimming after axonotmesis.

Peripheral nerve injuries are cause of sensory disturbances and in functional abilities, and are associated personal and social costs. Strategies that maximize nerve regeneration and functional recovery are necessary, the exercise is an option. This study evaluated the effects of forced swimming exercise on neuromuscular histomorphometry and on functional recovery in a median nerve crush model. Sixteen Wistar rats underwent median nerve crush and were divided into control group (CG) and swimming group (SG). The forced swimming protocol started one week after the injury and was performed for 1 hr a day, 5 days per week, for 2 weeks. The rats swam with an overload of 5% and 10% of body weight in the first and second week, respectively. The functional recovery was assessed in three moments using the grasping test. On day 21, fragments of the median nerve and of the forearm flexors muscles were removed for histomorphometric analysis. The SG had functional recovery impaired (P<0.001) and presented lower myelinated fibers number, fiber and axon minimal diameter, myelin thickness and g-ratio in the proximal e distal segments of the median nerve (P<0.005) and area muscle fiber (P<0.005) than CG. Also, the SG presented a number of capillaries in the proximal segments of the median nerve greater than CG (P<0.005). The exercise protocol used in this study impaired the regeneration of the median nerve and negatively influenced the functional recovery.

Effects of photobiomodulation therapy on functional recovery, angiogenesis and redox status in denervated muscle of rats.

OBJECTIVE: To evaluate the effects of photobiomodulation therapy in redox status, angiogenesis marker - vascular endothelial growth factor - and in the functional recovery in denervated muscle. METHODS: A total of 32 female Wistar rats underwent a crush injury and were randomly divided into four groups: Light Emitting Diode Group 2 and Control Group 2 (muscle collected 2 days after injury), and Light Emitting Diode Group 21 and Control Group 21 (muscle collected 21 days afterinjury). Light Emitting Diode Group 2 and Light Emitting Diode Group 21 received two and ten light emitting diode applications (630±20nm, 9J/cm2, 300mW), respectively, and the Control Group 2 and Control Group 21 did not receive any treatment. The function was evaluated by grasping test at four moments (pre-injury, 2, 10 and 21 post-injury days). The flexor digitorum muscle was collected for analysis of immunolocalization of vascular endothelial growth factor and redox parameters. RESULTS: Functional improvement was observed at the second and tenth post-injury day in treated groups compared to control (p<0.005). The muscle tissue of treated groups presented higher immunohistochemical expression of vascular endothelial growth factor. Photobiomodulation therapy decreased the oxidative damage to lipid in Light Emitting Diode Group 2 compared to Control Group 2 (p=0.023) in the denervated muscle. CONCLUSION: Photobiomodulation therapy accelerated the functional recovery, increased angiogenesis and reduced lipid peroxidation in the denervated muscle at 2 days after injury.

Effects of Photobiomodulation Therapy (LED 630 nm) on Muscle and Nerve Histomorphometry after Axonotmesis.

Peripheral injuries constitute a substantial clinical problem with unsatisfactory treatment. The study's objective was to analyze the effects of photobiomodulation therapy (PBMT) on median nerve regeneration and muscle recovery after axonotmesis. Twenty-four rats were randomized into three groups: control (CG), injury (IG), and LED therapy (LEDG). A 630 ± 20 nm (300-mW) LED was placed in contact with the skin. One point over the injury site was irradiated for 30 s, delivering 9 J (9 J cm-2 ). PBMT irradiation was performed once daily for 5 days followed by two-day interval and then more five consecutive days of treatment. Proximal and distal segments of the nerve and flexors muscles were removed for histomorphometric analysis using H&E staining for muscles and osmium tetroxide for nerves. The myelinated fiber and axon diameter and the myelin sheath thickness were greater in the proximal and distal nerve segments in the LEDG compared to the IG (P ≤ 0.05). The number of myelinated fibers was greater in the distal segment of the LEDG (P ≤ 0.05). The area, circumference, and diameter of the muscle fibers were larger in the LEDG than in the IG (P ≤ 0.05). The PBMT protocol used favored axonal regeneration and muscle recovery.

Effects of photobiomodulation therapy on functional recovery, angiogenesis and redox status in denervated muscle of rats / Efeitos da terapia de fotobiomodulação na recuperação funcional, na angiogênese e no estado redox em músculo desnervado de ratos

ABSTRACT Objective: To evaluate the effects of photobiomodulation therapy in redox status, angiogenesis marker - vascular endothelial growth factor - and in the functional recovery in denervated muscle. Methods: A total of 32 female Wistar rats underwent a crush injury and were randomly divided into four groups: Light Emitting Diode Group 2 and Control Group 2 (muscle collected 2 days after injury), and Light Emitting Diode Group 21 and Control Group 21 (muscle collected 21 days afterinjury). Light Emitting Diode Group 2 and Light Emitting Diode Group 21 received two and ten light emitting diode applications (630±20nm, 9J/cm2, 300mW), respectively, and the Control Group 2 and Control Group 21 did not receive any treatment. The function was evaluated by grasping test at four moments (pre-injury, 2, 10 and 21 post-injury days). The flexor digitorum muscle was collected for analysis of immunolocalization of vascular endothelial growth factor and redox parameters. Results: Functional improvement was observed at the second and tenth post-injury day in treated groups compared to control (p<0.005). The muscle tissue of treated groups presented higher immunohistochemical expression of vascular endothelial growth factor. Photobiomodulation therapy decreased the oxidative damage to lipid in Light Emitting Diode Group 2 compared to Control Group 2 (p=0.023) in the denervated muscle. Conclusion: Photobiomodulation therapy accelerated the functional recovery, increased angiogenesis and reduced lipid peroxidation in the denervated muscle at 2 days after injury.

RESUMO Objetivo: Avaliar os efeitos da terapia de fotobiomodulação no estado redox, no marcador de angiogênese - fator de crescimento endotelial vascular - e na recuperação funcional do músculo desnervado. Métodos: Um total de 32 ratas Wistar foi submetido a uma lesão por esmagamento e dividido aleatoriamente em quatro grupos: Grupo Diodo Emissor de Luz 2 e Grupo Controle 2 (músculo coletado 2 dias após a lesão), além do Grupo Diodo Emissor de Luz 21 e do Grupo Controle 21 (músculo coletado 21 dias após a lesão). Grupo Diodo Emissor de Luz 2 e Grupo Diodo Emissor de Luz 21 receberam duas e dez aplicações de diodo emissor de luz (630±20nm, 9J/cm2e 300mW), respectivamente, e Grupo Controle 2 e Grupo Controle 21 não receberam tratamento. A função foi avaliada pelo teste de preensão em quatro momentos (pré-lesão, 2, 10 e 21 dias após a lesão). O músculo flexor dos dedos foi coletado para análise dos parâmetros redox e da imunolocalização do fator de crescimento endotelial vascular. Resultados: Houve melhora funcional no segundo e décimo dia pós-lesão nos grupos tratados em comparação aos controles (p<0,005). O tecido muscular dos grupos tratados apresentou maior expressão imuno-histoquímica do fator de crescimento endotelial vascular. A terapia de fotobiomodulação diminuiu o dano oxidativo aos lipídeos no Grupo Diodo Emissor de Luz 2 comparado ao Grupo Controle 2 (p=0,023) no músculo desnervado. Conclusão: A terapia de fotobiomodulação acelerou a recuperação funcional, aumentou a angiogênese e reduziu a peroxidação lipídica no músculo desnervado 2 dias após a lesão.

Effects of two intensities of treadmill exercise on neuromuscular recovery after median nerve crush injury in Wistar rats.

Considering the potential action of exercise on neuroplasticity and the need to adapt protocols to enhance functional recovery after nerve injury, this study evaluated the effects of two intensities of treadmill exercise on nervous and muscular tissues and functional recovery after nerve crush injury. Wistar rats were distributed into sedentary group (SED), and 10 m/min (EG10) and 17 m/min (EG17) exercise groups. The exercise started one week after the injury. Ten daily sessions were performed with a 2-day interval after the fifth day. The flexor digitorum muscle and two segments of the median nerve were analysed histomorphometrically by light microscopy and computer analysis. Function was evaluated by grasping test, in 3 moments. Approval number: 016/2013. In the proximal segments of the median nerve, the diameter of myelinated fibres and axon, the myelin sheath thickness and the ratio of axon diameter to fibre diameter (g ratio) were significantly larger (P<0.05) in the EG10. The number of myelinated fibres was lesser in the EG17 than the other groups (P<0.05). No difference in the number of myelinated fibres among groups was observed in the distal segments, but the SED presented significantly larger axon and fibre diameters than those that performed exercise. The EG10 presented greater area and diameter of muscle fibres (P<0.05) and functional improvement observed on the 21st day after injury (P<0.05) compared with the EG17 and SED. Continuous exercise at 10 m/min accentuates nerve regeneration, accelerating functional recovery and preventing muscle atrophy.